Many types of luggage, such as backpacks or suitcases, are difficult to carry around when they carry significant weight. In this context, the term “luggage” includes sacks, bags, and other webbed, knitted, fabric, metal or plastic containers. Many types of folding carts and other devices, many of them built into a bag or suitcase, are available so that a person may tow his or her backpack or other bag on wheels. Most carts' built-in devices add unnecessary weight to the backpack or suitcase, especially when such functionality is not needed, such as when the backpack or suitcase is not full or has a light load. Other carts available for the transportation of luggage are bulky and therefore inconvenient to carry around.